In a porous crystal of zeolite low-silica X (LSX), β-cages and supercages (cavities) are arrayed in a diamond structure, respectively. We loaded potassium metal into zeolite LSX which has a chemical formula of Na 7.3 K 4.7 Al 12 Si 12 O 48 per β-cage (or supercage), and generated Na-K alloy clusters in β-cages and=or supercages. We have investigated the magnetic properties, the optical ones and the electrical resistivity at various values of K-loading density n per β-cage (or supercage) up to n = 9.7. Localized magnetic moments are observed at 8.2 < n < 9.7. Almost simultaneously, nearly pure ferromagnetism is observed at 8.4 < n < 9.7. The highest Curie temperature is ≈12 K at n ≈ 9. Optical reflection spectra for 8 < n have a new band at 2.8 eV which is assigned to the optical excitation of s-electrons of clusters generated at β-cages. The origin of the magnetic moments is assigned to these β-cage clusters because of the coincidence between the growths of the 2.8 eV band and localized magnetic moments. The origin of magnetic ordering is explained by a ferromagnetic interaction between β-cage clusters. All samples are found to be insulating from the temperature dependence of electrical resistivity. A direct magnetic interaction between β-cage clusters is not expected because of the high electronic barrier between them. A ferromagnetic superexchange coupling between β-cage clusters is newly proposed via the sp 3 -like closed-shell clusters at supercages. A thermal hysteresis is observed in the electrical resistivity at intermediate temperatures, and the origin is assigned to low-density carriers generated in the Na-K eutectic alloy structures in nanospace.

Fe 60 Pd 40 nanoparticles were prepared by sonoelectrodeposition. After annealing at various temperatures from 450°C to 700°C, the nanoparticles were found to have an ordered L1 0 structure and to show hard magnetic properties. Among the samples investigated, the nanoparticles annealed at 600°C exhibited the highest coercivity which amounts to 2.31 kOe at 2 K and 1.83 kOe at 300 K.

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In zeolite low-silica X (LSX), β-cages with the inside diameter of ≈ 7 Å are arrayed in a diamond structure. Among them, supercages with the inside diameter of ≈ 13 Å are formed and arrayed in a diamond structure by the sharing of windows with the inside diameter of ≈ 8 Å. The chemical formula of zeolite LSX used in the present study is given by NaxK12−xAl12Si12O48 per supercage (or β-cage), where NaxK12−x and Al12Si12O48 are the exchangeable cations of zeolite LSX and the aluminosilicate framework, respectively. Na-K alloy clusters are incorporated in these cages by the loading of guest K metal at nK atoms per supercage (or β-cage). A Néel's N-type ferrimagnetism has been observed at n = 7.8 for x = 4. In the present paper, optical, magnetic and electrical properties are studied in detail mainly for x = 4. Ferrimagnetic properties are observed at 6.5 < n < 8.5. At the same time, the Curie constant suddenly increases. An optical reflection band of β-cage clusters at 2.8 eV is observed at n > 6.5 in accordance with the sudden increase in the Curie constant. An electrical resistivity indicates metallic values at n 6, because a metallic state is realized in the energy band of supercage clusters. The ferrimagnetism is explained by the antiferromagnetic interaction between the magnetic sublattice of itinerant electron ferromagnetism at supercage clusters and that of localized moments at β-cage clusters. The electrical resistivity in ferrimagnetic samples at n = 8.2 for x = 4 increases extraordinarily at very low temperatures, such as ≈10 6 times larger than the value at higher temperatures. Observed anomalies in the electrical resistivity resembles the Kondo insulator, but itinerant electrons of narrow energy band of supercage clusters are ferromagnetic differently from the Kondo insulator.